The latest version of Lumion free (or whatever its called these days) should support a reflection/clip/bright slider in the standard material. It's the bright part that will enable you to drive material emissiveness through the diffuse texture its alpha-channel in combination with the emissive slider above it.

I used to create emissive materials of any kind of color by manipulating the glass material.Now this is not possible anymore in lumion 3.1.2. Is there any reason why this slider was taken off? What a loss?